conventionally, there is proposed a technique of purifying exhaust gas by using an electrically heated catalyst (hereinafter suitably referred to as “EHC”) provided on an exhaust passage. For example, in Patent Reference-1, there is proposed a technique of determining an abnormality of an EHC by using a NTC (Negative Temperature Coefficient) characteristic showing that an electrification resistance value of a catalyst carrier varies dependently upon temperature variation of the catalyst carrier.